Method of casting metal



Patented Apr. 28, 1931 "UNITED STATES PATENT orries EARL C. SMITH, OFCANTON, OHIO, alSfiIGNOIR. TO REPUBLIC STEEL CORPORATION, OF

YOUNGSTOWN, OHIO, A CORPORATION OF NEW JERSEY METHOD OF CASTING METAL HoDrawing,

The present invention relates broadly to the art of metal founding andmore particularly to an improved method having a special value withreference to the casting of relatively large bodies of a more or lesssolid nature or having sections of substantial-cross sectional area,such, for example, as those present in ingots. 7

It is well recognized in the art 'to'which m the invention relates thatat least alarge part of the dificulty in the casting of ingots arisesfrom the manner in which the molten metal solidifies or freezes.Ordinary deadmelted steel freezes at a rate substantially proportionateto the square root of the time in'niinutes. In other words, the firstinch freezes in approximately a minute, two inches inapproximately 4minutes, 5 inches in a PIOXI- mately minutes, etc. It will thus e seen20 that a. inch ingot requires substantially 225 minutes to freeze tothe center. In actual ractice the outer shell freezes very quick y andthe inner liquid portion tends to tear itself to ieces during freezing,due to 25 shrinkage. I the rate of freezing could be accelerated in theinner portion of the ingot, this danger of tearin to pieces would beminimized and no di culty would be encountered. The present inventionhas for so one of its objects the controlling of the freezing so as toeliminate difiiculties with respect to shrinkage, preferably by insuringfreezing of the lower portion of.the ingot before the sink head is outof action, whereby there is no efficient filling of any shrinkagecavities.

In the pouring of most ingots, it is necessary to pour at temperatureshigh enough to insure fluidity and to take care of certain reactions. Inorder to secure the desired condition it is customary to err on the sideof too high a temperature so that the furnace operator usually deliversmetal into the ladle at too hi h a temperature, and this is in turnpoured into the molds with this extra temperature. In accordance withthe present Application filed November 26, 1827. Serial No. 288,006.

a more or less volatile character, having a boilin point below thetemperature of the metal eing cast in order to insure volatilir-zation.The heat of'vaporization of such added materials, either metallic ornonmetallic, is usually very high and advantage can be taken of the heatabsorbtion thereof to enable the cooling of the interior of the ingotduring pouring and freezing to be satisfactorily controlled.

In accordance with the present invention, I preferably add to the metal,either imme diately prior to or during the pouring operation,a volatilematerial such as lead, fluorides, or other materials, characterizedbythis boiling action, and take advantage of the heat absorption thereofto increase the rate of cooling of the interior of the ingot.

By the use of the present invention, the production of castings, such asingots, having a more uniform and desirable texture is insured and therate of solidification is hastened. The materials added, due to theirvolatile nature at the temperatures present, do not interfere with theobtaining of the desired characteristics in the finished product. Theinvention is obviously not limited to any specific castings ormaterials, and is important not only with dead melted steels, but withopen steel ingots after pouring.

I claim 1. In the method of forming metal castings, the step comprisingadding to the interior of the casting while in molten condition anartificial refrigerator in the form of a solid material having a highheat of vaporization and volatilizable at the temperature of the metalfrom which the casting is to be made, and utilizing the heat absorptionof such material during-volatilization to hasten the cooling of theinterior of the casting.

2. In the art of casting metal ingots, the method which consists inadding to the metal 5 while in a molten state a solid volatile materialhaving a boiling point below the temperature of the molten metal andpermitting such added material to reach a state of volatilization, thesaid volatile material functioning during the process of volatilizationto extract heat from the interior ofthe ingot and expedite the coolingaction thereof. In testimony whereof I have hereunto set my hand. EARLC. SMITH.

